Windows 8's handling of HiDPI displays still leaves a lot to wish for. There is still just one "right" DPI setting, the "normal" scaling and anything other than that causes small artifacts on some apps due to the text being scaled up but some other elements not. It gets even worse if you connect an external monitor that has a lower pixel density and thus should use a lower DPI setting. You can't set different DPI's for different displays so one of them ends up looking ugly and just a bit off.
This is something that OSX does great. I have a Macbook Pro with the 220 ppi Retina display and a 27" Thunderbolt display. They use different DPI values and the transition is seamless even when dragging windows from one screen to the other. If I boot to Windows one display becomes basically useless. Either everything is way too small on the Retina display or everything is way too big on the external monitor.
But anyways, the Pixel is a normal x86 machine so I'd imagine it should be possible to install other operating systems on it.